Swordfishy/ASPEN FETZILLA power amp - Page 54 - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > AKSA

AKSA Builders of market proven kits and modules at sound quality to rival the best in high end

Reply
 
Thread Tools Search this Thread
Old 1st October 2011, 10:01 PM   #531
JKC is offline JKC  Canada
diyAudio Member
 
Join Date: Jun 2011
Location: Calgary
Here is my finished version of Fetzilla amp. I was playing music for the last two days and I am really impressed by quality of sound. Bass and vocals are excellent. Piano sound is as close to real thing as you can get in both classical and jazz music. Also guitar sound is very detailed and real without any coloration. Sorry guys for not using any poetic language for sound description but I will leave that for others who didn't built it yet. It is a keeper for me, thank you to all contributors to this project.

George
Attached Images
File Type: jpg Fetzilla finished Oct1-2011_0012 copy.jpg (202.3 KB, 501 views)
  Reply With Quote
Old 1st October 2011, 11:17 PM   #532
diyAudio Member
 
Join Date: Nov 2010
Location: Marblehead Ma
very nice JKC ! my boards are pretty much done except for silver micas and auricap which i'm waiting for from partsconnexion .

was your build pretty much stock ?

thanx for the good review . looking forward to hearing mine .

cheers Woody
  Reply With Quote
Old 1st October 2011, 11:25 PM   #533
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
George,

Beautiful work, very elegant, like the VUs a lot!

But, I note it is a JKC 787 (is that a Dreamliner?) case, not a FetZilla!!

I enjoyed your description of the sound, you will make an audio novelist yet!

I live in hope that others, as they complete their FetZillas, will post their impressions - good and bad, let's keep it credible - on this thread. It is fitting closure and appropriate feedback for what has been a very successful design, and indeed, Group Buy.

Cheers,

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 2nd October 2011, 02:43 AM   #534
JKC is offline JKC  Canada
diyAudio Member
 
Join Date: Jun 2011
Location: Calgary
Woody,

Actually, my build is anything but stock. The major difference from original design is stand alone power supply with bigger transformers and bigger filtering caps. Because of that I used only 3300uF on the board itself to make it even faster in big current swings. I also used two additional circuit boards, one for soft start and another for VU meters. Another change I have made is zobel network at the output. I used pi filter there with those values: 47nF/8.2ohm, 2uH with 2ohm in parallel, 68nF/5.1ohm (this leg mounted on output terminals). That is all. Currently I am running this amp with VAS at 13mA and bias 450mA settings. Have fun.

Hugh,

Thanks. It is just name and has nothing to do with the planes . I have Fetzilla name on the back plate however, so nothing is lost.

George
  Reply With Quote
Old 2nd October 2011, 07:59 AM   #535
diyAudio Member
 
acidbrain's Avatar
 
Join Date: May 2008
Location: Groningen
Your FetZilla AMP looks great George ! How did you manage to connect the VU-meters without forming a load to the signal ?
  Reply With Quote
Old 2nd October 2011, 07:17 PM   #536
JKC is offline JKC  Canada
diyAudio Member
 
Join Date: Jun 2011
Location: Calgary
Acid,

You can't connect VU meters directly to the output. I used separate high impedance circuit with 4 op-amps to drive VU meters.

George
  Reply With Quote
Old 2nd October 2011, 07:42 PM   #537
diyAudio Member
 
acidbrain's Avatar
 
Join Date: May 2008
Location: Groningen
That I know, but still output is used to drive the VU-circuit. Anyway, you did a very good job creating an "old skool" look.

Erik.
  Reply With Quote
Old 2nd October 2011, 10:15 PM   #538
JKC is offline JKC  Canada
diyAudio Member
 
Join Date: Jun 2011
Location: Calgary
Erik,

Yes, signal for VU meter is taken from the output into 100K impedance buffer/amplifier, so it is transparent to the load and not affecting anything.

George
  Reply With Quote
Old 3rd October 2011, 01:51 AM   #539
diyAudio Member
 
Join Date: Feb 2008
Location: Melbourne
At last I have finished my pair of FETzilla monobloc amps. I have used Hugh's NAKSA-70 chassis, in which the FETzilla fits very nicely. The chassis is one piece of folded 3mm aluminium, and acts as the heatsink. At a bias of 390mA, I can only just feel some warmth under the mosfets.

I too am very impressed by the sound.

Paul Bysouth


Lovely work, Paul, very neat and tidy. Congratulations! HRD
Attached Images
File Type: jpg PB_FETzilla.JPG (480.1 KB, 417 views)

Last edited by AKSA; 3rd October 2011 at 02:06 AM.
  Reply With Quote
Old 4th October 2011, 12:31 AM   #540
diyAudio Member
 
Join Date: Nov 2010
Location: Marblehead Ma
hey guys , a few questions ...

1. is there a reason that Rz needs to be inside of the inductor instead of just mounting on the underside of the board where we've already got the mosfets and power supply cap resistors ?

2. what is the final determination on silver mica's c5 & c6 . i recall Hugh saying they were needed , but was that just for difficult speaker applications or needed in all situations ? i notice that JKC didn't use them .

3. in adjusting P1 , where are you measuring bias current ?

i really appreciate all your newbie friendly advice and help

cheers Woody
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Aspen Headphone Amp AKSA AKSA 1129 2nd June 2011 05:48 AM
Aspen Maya Vegking AKSA 7 17th May 2011 05:02 AM
DIYaudio to become new Aspen Forum AKSA AKSA 13 2nd May 2011 07:04 AM
Sachiko/aspen slab rmcelroy Full Range 0 9th March 2011 06:34 PM
Aspen HAKSA Group Buy AKSA AKSA 74 16th November 2010 05:17 AM


New To Site? Need Help?

All times are GMT. The time now is 09:17 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2